Conductor



Dec. 18, 1951 w. EDWARDS 2,579,227

CONDUCTOR Filed July 16, 1945 INVENTOR. firing Wfi'afimras BY ATTOR EYS I Eatented fiec. 1 8, 195i s UNITED STATES PATENT OFFICE CONDUCTOR Irving W. Edwards, Detroit, Application July 16, 1945, Serial No. 605,319 7 Claims. (of. 287-2035 This invention relates to electrical connecting conductors, and more particularly to conductors of the type commonly known as jumpers or ground straps used for establishing electrical continuity.

The principal object of my invention is to provide an electrical connection or bond of thistypewhich may easily be applied by workmen in the art and which provides a good electrical connection which is maintained secure in spite of shocks and vibrations or other factors which tend to loosen or impair the connection.

My connectors are particularly applicable as rail bonds and may also be used to establish electrical connections to such structures as stee shapes, bus bars and pipe lines.

In railway track circuit signalling which is an important field of use of my connector or bond,

it is the practice electrically to connect each rail to the next by an electrical conductor or rail bond of low enough resistance efliciently to conduct the relatively small signal currents along the rails. The bond ordinarily com-prises a flexible electrical conductor long enough to extend from a point near the butt end of one rail toa similar point near the butt end of the next, with suilicient slack to allow for vibration and exa centrally within the stud, and a pin is placed in this stud bore, afterwhich the stud is hammered into the bore of the rail head, thereby wedging the pin in the stud bore to expand the stud against the rail bore and hold the connector in place.

I have found that such prior known connector while many times giving good service, frequently cause trouble, sometimes because of imperfect electrical connection or breaking of the stud and sometimes because the stud can be vibrated out of the hole. I have overcome these undesirable features of the prior known connector studs by the use of a centering ball, preferably of a very hard metal with a polished surface such as a hardened ball bearing. vI accommodate this within a tapered recess formed within the stud from which a part of the ball protrudes beyond the end of the stud. Furthermore, I provide the bore in the rail with a cupped or conical-base.

By reason of the proportioning of the parts so thatthe ball located in the recess of the stud projects somewhat beyond the end of the stud, provision is made for the ball to center itself at the cupped base of the bore in the rail head, thereby bringing the stud to a centered position. Because of this centering feature, the stud can be driven home by hammer blows without undesired cocking or offsetting and a secure sealing against moisture and locking of the stud in the bore is provided with attendant good electrical connection. This sealing and locking of the stud in the bore occurs primarily at the region near the outer end of the stud, resulting in the efficient type of locking had by use of my'connector, with little or no tendency of th stud to shear or break off at the base.

By appropriately shaping the stud recess, I am enabled by the use of the ball, to adapt the connector to many kinds of applications, both as rail bonds and as connectors for other purposes.

Another feature of my invention is the'provision of a parallel arrangement of a plurality of electrical connecting cables to the terminal. Not only does this tend to maintain better electrical continuity, but it also has a mechanical advantage of adapting itself to a desirable serpentine form of crimping whereby an excess length of the cable can be held close to the memthe railheads of a pair of abutting rails, showing the rails connected by a rail bond according to my invention;

Fig. 2 is a :partial vertical cross-section view through a railhead, taken at line 2--2 of Fig.1,

showing the connecting stud and .its cable;

' Fig. 3 is. a front elevation view of the railbond shown in Fig. 1;

. Fig. 4 is a vertical cross-sectional view showing part of a rail, the cross-section being taken through a stud hole in the railhead, forv example at line 4-4 of Fig. 1;

Fig. 5 is an enlarged partial view. partially. in

--'cross-section, taken at the same horizontal section as Fig. l, and showing in detail'the'co'nstruction of the stud with its recessand ball;

Fig. 5a shows graphically the pressure distribution of one of the driven studs of my invention; 4

Fig. 6 is a side view of the stud of Fig. 5. made A recess 26 is provided centrally within the end of each stud. The recess is so shaped that its widest dimension or diameter is near the end of the stud at a position 21, and narrows down toward the base 28 of the recess. The recess is purposely so shaped that its successive cross-sections in going from the outer end of the stud toward/the base-28 are circles of decreasing diameter. This shape of the recess enables a ball .30 to be placed in the recess far enough so that the' maximum diameter of the ball goes down vention adapted for connection with a metallic member or the like, and showing ,,a multiple cable entry into the sleeving attached to the stud.

In Fig. 1 there are shown the abutting ends of the heads of adjacent rails ll andfl "in'-a railroad track, the endsiof the rails having the usual clearance between them. In :thefigure, the rails are shown in a horizontal cross section taken at lines l-l of .Fig. :2 andof Fig. 4. Fig. 2 shows a vertical .cross-section through :ra'il H, s-the topbf the rail on which the wheelrollsbeing -indicated'as l3. Fig. 4 shows avertical section "through rail [2, the top of therail being marked "I 4. ln'each of Figs. 1,2 and 4,.only a portionof ithe-section through the rails is shown, enough to" illustrate the applicationof my invention.

For the purpose of applying my connector to the rails, I provideabore in the side 0f the railhead near .the abutting-end of each rail, the :bore in rail ll being numbered and-the bore irprail l2 being numbered 15. Each'bore'is of a cylindrical shape such :as maybe made by an ordinary drill, and the end ofeach boreis brought to somewhat of a point or apex which may be,

for example, cone-shaped, as shown at 116a in Fig.

ipast the edge of the recess at 3|. The ball can accordingly be held against falling out of the recess byerimping in the leading edge 3| of the 4. This shape need not necessarily be exactly conical, nor brought to a definite point, but should be cupped somewhat similar ito a cone, "so thaw ball may readily set itself therein in fone definite position. This shape of the :base or terminationof the bore, I call herein cup-shaped regardless of whether lit is exactlyficonical or "somewhat curved or rounded.

For the purpose of electrically connecting the abutting rails, I provide a connector I! accordingitolmyinvention. Thetconnector', or .rail bond [1 comprises an electrical conducting cable, or preferably :a :plurality of parallel cables L8, .ter- 'minated' at their 1respecti-ve"-:ends tin terminal members tlflnand 19a. The arrangement used for fastening ithe'cable to the terminal members is -a system ofconcentric sleevesZO :and12 I, welded terminal 19; and sleeves 20c and 1 l a welded toterminal 19a. To make the :connectionpthe heads 22 and vzzalmay be -.-concaved to :some extent at their ends next to the cable; and the outer sleeve '2! with the inner sleeve 2.0 firmly .telescoped in it, is then setinto :the cavity and welded at 23. Similar construction is used at the other end of 'the cable at .2011, 21a, 22a and The cable wires themselves may ibe 'suit-.

stud around-the ball, as shown in Fig. 5, while still allowing somewhat less than a hemisphere of "the-ball to protrude at 32, beyond the stud. The ball is preferablyrof a very hard non-defformable material, such as a :hardened steel ball- 'bearing, and "its surface isfpreferablyprovided withza :good smooth finish or polish. The material .of the stud :is ilkewise a :metal "but notas hard as the ball. It may be made of a .somewhat softer steel 101 of abronze-or the like, which will :flow when forced by the hard ball.

To establish a connection by the use of my connector, the stud is inserted into the bore -l5 iand'then driven by-a suitable driving or hammering operation. ;If the outer edge of the stud is tapered, as described above, the stud can easily be started, and can :have a shape to conform with the cupped'bottom 16a of the bore.

Q Asxthe stud isypushed .into the bore, .it should be preferably fit snugly, although :it can be well .tfastenedinto the bore even though :the :bore' be somewhat" oversize. The :forward part ofthe 'ball should be set against the inner conical .or

cuppedpart of the bore-at the circle of contact marked-:33 inFig.-5, which "will serve to center the ball. and stud even .though :there' may be some other slight misalignment'between the stud and the bore. The stud should be proportioned so that; when the ball strikes the conical or cupped :portionavof :the bore, 'the :forward annular edge 3|. of the stud should remain-separated-at some distance from theend Ga-of the bore as-shown 'in'Fig. 5.

:For thBDIiIDOSBsDf the driving, it will be con- 'venient to applyaa drivin punch to the-recessed head 22a of the stud,-.and :then hammer on the punch. Upon :the commencement of the hammering, the :driving of the stud further forward against the maximum diameter of the ball will serve "to expand :the stud outwardlytoward a :larger diameter near :its forward end at about the. 1positiontof maximum diameter of the ball, 'thereby'lockirig the stud to "the rail near :the 'forward'iend'rof the stud. This initial lockin serves as .azba'cking by'which the stud isfurther upset:=prcgressively,upon further driving, so that the locking area progresses from near the tip end'fo'f the stud toward the base -of the stud.

l'upsetting and "locking will continue progressively "as the stud'is driven so Ethat the ball lis forced ffurther and further inward into the recess of continually diminishing cross-sections.

Asa rough approximation, the area of .greatest pressure tending to bind the stud into the .b'ore' existstromthe region of abou't point 34 to'point 35 around thestud. There is little or no pressure at the tip end of the 'stud zliinasmuchas the main-diameter of the ball 'is considerably further into the recess than this point. -Fu'rthermore, since thebase 28 of the recess-is at the wall, there isthen appreciably less than the maximum pressure at the base 29of the stud against the outer-edge of the wall. This gradient of bindingorlooking pressure of the stud against the wall is illustrated graphically fora railhead bond in Fig. a, and contributes .greatly to the efficient bonding and holding effect.

of my bond, while at the same time efiecting an efiicient seal against seepage into the bore, and providing a good electrical connection of the bond to the wall. In Fig. 5a. the ordinate is. sealed in accordance with distances along the stud, and pointson the ordinate scale are transferred directly across from corresponding points of the stud in Fig.5. The abscissas represent units of pressure of the stud againstthe bore in the railhead. As will be seen from the curve, the maximum binding pressure occurs at region 36, which is the region of maximum diameter of the'ball. The region of high pressure extends inwardly as far as region 34 of thestud which is approximately the original place of maximum diameter at the ,bore before the ball started to move inwardly into the recess. Owing to the fiow'of stresses, the high pressure region continues for a distance toward the base of the stud, approximately to the point 35, at about the base of the seating ball. From this vpoint the pressure drops off quiterapidly as at 44 where con-. tactof the ball with the stud ends. At the extreme tip 21, the pressure is approximately zero.

'- Adesirablepressure relationship for typical bond installation, in, railheads is shown in the pressure diagram, Fig. 5a; but for installations where impact or vibration is less, as in pipe line shunts, and where the greatest degree oiconductivity is essential, the ;pressure areas can be modified throughout the length of the stud by changing the diameter of the ball, the taper or contour of the recess within the stud, and altering the physical propertiesof the stud or the length of the recess therein. For instance, a small ball necessitates a relatively thicker wall of the stud at the tip andwitha shallow recess the main body of the stud would be comparatively e u atheis w ul n o uqe a m e "3 s r 3.? 1. while 1 1. u settin ct on e dw u d .ex anditat th n: trance into the bore, say 29, which would tend to block off further upsetting inwardly toward the relatively distant v bottom of the recess 23, thus giving a maximum oi wall pressure at the point of entrance of the stud in the bore. Such a design would be required to insure the utmost insealing of the bore against seepage (of corrosive brine, acids or gases. Figl 9 shows a modificationi of the' stud conf struction adaptedfor. use with shallowerdevices than railheads, for example with metal plates of limited thickness. In this figure, thelstud 31 is shorter with respect to its diametertuams' the stud in Figsfi to 8; and it is proportioned this way in Fig. 9 to" accommodate itselito "the rather shallow, flat piece of metal 33, into which it is inserted. Apart from the change in; p ro portion, the construction is similar-toithat in Figsl to 7 and involves the useof the ball 36 inserted in the recess26 of the stud andfitted against the cupped base of the bore.

The cable arrangement comprises a sevenstrand rope construction cable comprising the seven cables side by side, as shown in Figs. 8 and 9. Preferably, the cables are arranged'so that the lays of the cablewires arealternately individual wires of contiguous strands lie in. the same direction, thereby reducing wear under vibration which might otherwise occur if the wires of the lays were crossing each other where they are in contact. These are placed within the oval-shaped sleeve 40 which is telescoped .within the larger similar shaped sleeve. 4|. The two sleeves are telescoped within the head 42 of the studwhich in this embodiment has an. oval cross-section similar to that of the sleeves. These sleeves are preferably compacted. and sweated together to insure efficiency in driving, particularly in the region of the stud. The stud may be soldered, sweated, brazed or weldedlat its solid end as indicated at 43, to the cable and sleeve of the terminal. By my invention, I have provided a connector adapted for use in many situations and especially suited for use as a railbond. My connector is characterized by the simplicity of its application and the ease of its installation with comparatively untrained labor, coupled with its essential permanence and good electrical con -v nection. By reason of the arrangement of the ball held in its socket or recess by the crimpedover tip of the stud, the connector can be carried around without loss of the ball. 1

By reason of the conical or curved tapering or cupping of the base of the bore in the memberto be connected, in cooperation with the ball in the socket, the connector is self-centering, that is, the ball is automatically centered into the bore. This feature substantially reduces or eliminates the tendency of misalignment of the stud in the hole, that is, avoids the tendency to cooking over or faulty driving, which has" heretofore been experienced in the use of prior-known connect--v ing devices. Furthermore, the permanence. or holding capacity of my stud connector is greater than that heretofore experienced in the use of stud connectors. This greater holding effect is doubtless due to the progressive upsetting of the metal of thestud as the ball progresses into the recess, over a substantially large area at the circumference of the stud, coupled with the fact that this binding or high pressure area exists from near the tip of the stud rather than from near'the base. By reason of this form of pressure gradient, as illustrated in Fig. 5a, the'pounding of heavy locomotives and cars on the tracks does not have as much effect in loosening my stud as in the case of prior known connectors; and furthermore, owing to the lack of excessive binding pressure at the base of the stud, that is the rail face, the vibration and shocks are not asapt to break ofi the stud there. Moreover, by reason of my construction, comprising the above-noted type of gripping action there is not as much tendency nor need, usually, for the stud to upset or deform at the base, as inure use of the other types of connectors. Such excessive. upsetting near the base of the stud is an extreme disadvantage as it would tend to resist further driving in of the stud near its end and thereby reduce the desired holding effect near the tip of the stud. The progressive increase of the gripping area from nea'r'fthe tip toward the base has a further advantage of squeezing out from the bore hole of any unde sirable moisture or other foreign matter which might be condensed or introduced into the hole, thereby minimizing the presence of substances which might otherwise tend to produce high re.- sistance or corrosion in the connection.

Qltlyconnection maintains throughout a long ductivity; inasmuch. asthe ball is. always mains taineddn firmcontactwith the cupdof the. bore, while at the same time the metal, of the stud is firmly. bound, against. the wall of. the, bore over awidearea;

My. novel. bond construction isv furthermore especially well suited for extraction from a rail or other location. by simple extracting means without breaking off of the stud in the rail or device. This results from. the fact that the maxi:- mum holdingpower is toward the tip end -.of:the stud ratherthan the base. end. In consequence, when a pulling. or extracting force is applied between the railhead and the head of the stud, the stud tends to neck down somewhat at. its base-at 29, andthis necking down tends to continue progressively toward the tip end of the stud-,-- until thestud is finally freedwithout break- The tendency toward loosening or actually falling out from the railhead of prior known types of-connectors has been due to a lack of sufficient gripping-or holding power, in thecase of studs which can be easily underdriven; while in the case-of those prior known kinds of connectorsin which the studs can be overdriven, the studs have often actually forced themselves out by reason of the excessive pressure from their own overdriven flowable elements. By reason of my studconstruction, however, this danger of loosening and falling out is greatly reduced or eliminated by-reason of the stable, virtually incom pressible and distortion-resistant ball embedded in atough shell-of'the stud which is only somewhat less hardthan the ball. My design encompass es two distinct means of expanslon 'of the stud; one agency is the expansion by means of the wedging of'the ball, localized near the tip of the stud, and the other is the upsetting of the tud. itself. th s ps in be ng. u qu n to the wedgingby the ball and carried onprogressively and controlled by the contour or the rec s t any equire de e in he s c s withg t i ter u i the o nui y- The arrangement of telescoped connecting sleeves has, particular advantage in rail bond work wherein the cables are subjected to heavy vibration, because the sleeves tend to protect the cable against damage from the vibration. B'y reason of' use ofthe plurality of telescope d sleeves, with the inner sleeve extending further out along the cable than the outer sleeves which terminate near the head, the rigidity-of the cable connection or termination is increased toward the head. This progressive increase in rigidityor increase of stiffness toward the connector head plays a, very important part in absorbing vibrations. In addition to the function of allowing more flexibility toward the-outer end of the inner sleeve than atthe head itself, these telescoped connector sleeves have the additional advantage or -increasing the dampening effect. The reason for thisis" thatithe;individual.vibr tionairesoe nan efrequenciesof-the several telescopedasleeves willi e .difierent and inconsequence they. wi lnot all vibratenaturally. atthe same. period;

My useof parallel cable wireshasaiurther advantage ill that it i possible, to obtain ..a S811: pentine. effectofithe, cable. as shown in Fig. '1. by. the use of; multiple cables. whereas. by the useof only a single; cable only asingle loop of the cablesuch as shownin Big. 1. would be practical. The. ability to .form into .the serpene. tine shape is. ofaconsiderable advantage, which resides in. the.- fact. that. agiven over-all. length of cable can be brought closerto the. rail itself thanwhen. only-a single loop ,is. used as shown in Fig. 1. Itisanadvantageto have the cable and the .terminalheadhugclose totherail, as in this way-itis less apt to be. damaged by extraneousdevices or tools brought in. proximity to it, or by vehicles. passingover the track and dragging equipment'over the. rails and-the cables.

It will be recognized from the foregoing description and statement of advantages that my connectors-are useful in many applications, and are not necessarily limited to rail bonds or the particular applications mentioned. Further-- more, it will be apparentthat it is not necessary to put connecting studs on both. endsof" the cable, as in some casesit may be desirable,- or required, only toput the stud on one end for connection with an-electrical'member, while attaching the other end-of the cable to a position or terminal in some other manner, for example, soldering or welding.

I claim:

1. An electrical terminaladaptedto be-locked within a boreprovided-in-a member to be connected with the-terminal, said terminal comprising a head adaptedto be driven, a stud-pro-' trudingfrom the head and adapted to be inserted within the bore, a recess centrally located within the endof thestud remote from the head, a ball ofharder material than the stud permanently anchored within the recess and only partially protruding fromthe'end of the stud in the unexpandedcondition of thestud so as to engage the base of'the bore when the studis inserted thereinto, the cross-section areas of the recess-in the unexpanded condition ofthe-stud progressively and uninterruptedly diminishing from the cross section substantially-at the max} diameter offthe ball inwardly towardthe head otthe terminal and to a point spaced inwardly of the ball.

2. For usewith an electrical conducting member having a cylindrical bore terminating in a cupped base, an electrical terminaladapted to be locked within said bore, said terminal com prising a head adapted to be driven, a cylindrical stud protruding from the head and adapted to be inserted within the bore, said stud having a recess centrally located within the end of the stud remote from the head, a spherical ball of harder metal than the stud metal permanently anchored within the recess so as to protrude through the'outer end'of the recess beyond the end of the stud when the latter is in unexpanded condition, said ball having the major portion thereof housed within the recess and being spaced from the bottom of the recess to permit the ball to move inwardly within the recess to expand the stud within the bore upon driving the head, said recess in the unexpanded condition of the stud having the walls thereof progressively tapering inwardly from a point sub- 9 stantially at the diameter of the ball to a point spaced inwardly of the ball.

3. For use with an electrical conducting member having a cylindrical bore terminating in a cupped base, an electrical terminal adapted to be locked within said bore, said terminal com- 7 prising a head adapted to be driven, a cylindrical stud protruding from the head and adapted to be inserted within the bore, said stud havin a recess centrally located within the end of the stud remote from the head, a spherical ball of harder metal than the stud metal permanently anchored within the recess so as to protrude through the outer end of the recess beyond the end of the stud when the latter is in unexpanded condition, said ball having the major portion thereof housed within the recess and being spaced from the bottom of the recess to permit the ball to move inwardly within the recess to expand the stud within the bore upon driving the head, said recess having the cross-section areas thereof progressively diminishing inwardly from a point approximately at the diameter of the ball when the stud is in unexpanded con- ,dition to a point spaced inwardly of the ball.

4. An electrical connector adapted for connection into a bore having a base, said connector comprising a head and a stud having its base at the head, said stud being adapted to fit into the bore and having a centrally located recess formed in its outer end, a spherical ball mounted within the outer end of the recess in such p0 sition as to protrude beyond the end of the stud in the unexpanded condition of the stud, the outer portion of the recess being in the form of a socket smoothly embracing more than a hemisphere of the ball to anchor the same within the recess in spaced relation to the bottom of the recess, the circular cross-section areas of the walls of the recess in the unexpanded condition of the stud progressively and uninterruptedly diminishing from approximately the circular cross-section area of maximum diameter of the socket toward the base of the stud to a point spaced inwardly of the ball, whereby as the ball is driven into the recess the degree of lateral pressure exerted thereby against said walls will progressively increase and the ball will be locked within the recess in any position thereof.

5. An electrical connector adapted for connection into a bore having a base, said connector.

comprising a head and a stud having its base at the head, said stud adapted to fit into the bore and having a centrally located recess formed in its outer end, a spherical ball of harder material than the stud mounted within the outer end of the recess in such position as to protrude beyond the end of the stud in the unexpanded condition of the stud, the outer portion of the recess being in the form of a socket smoothly embracing more than a hemisphere of the ball to anchor the same within the recess in spaced relation to the bottom of the recess, the circular cross-section areas of the walls of the recess in the unexpanded condition of the stud progressively and uninterruptedly diminishing from approximately the circular cross-section area of the diameter of the ball toward the base of the stud to a point spaced inwardly of the ball, whereby as the ball is driven into the recess the degree of lateral pressure exerted thereby against said walls will progressively increase and the ball will be locked within the recess in any position thereof.

6. Anelectrical terminal adapted to be locked within a cylindrical bore provided in a member to be connected with the terminal, said terminal comprising a head adapted to be driven, a cylindrical stud protruding from the head and adapted to be inserted within the bore, a recess centrally located within the end of the stud remote from the head and terminating at its outer end a substantial distance away from the head, a ball of harder metal than the stud permanently anchored within the recess a distance from the inner end thereof so as to protrude from the outer end of the stud in the unexpanded condition of the latter, said recess in the unexpanded condition of the stud having circular cross-section areas which diminish in size progressively from a point corresponding substantially to the diameter of the ball in the direction of the base of the stud and to a point spaced inwardly of the ball, said ball being adapted to engage the base of the bore and the surface of the recess, whereby driving of the stud into the bore causes the ball to enter further into the recess with attendant flowing and expansion of the stud metal in front of the greater diameter of the ball and against the wall of the bore so that the locking pressure of the stud against the bore is initially along the surface of the stud near its tip.

'7. An electrical terminal for a flexible electrical conducting cable comprising a head adapted to be hammer driven, a cylindrical metallic stud protruding from the side of the head opposite that to be driven, a recess centrally located within the end of the stud remote from the head, a ball of harder metal than the stud metal permanently anchored within a socket in the recess a distance from the inner end thereof so as to protrude from the outer end of the stud a distance less than a hemisphere in the unexpanded condition of the stud, said recess in the unexpanded condition of the stud having circular cross-sections which progressively diminish in size substantially from the mid point of the socket in the direction of the base of the stud to a point spaced inwardly of the ball, whereby when the stud is driven into a bore the material of the stud will flow forward of the maximum diameter of the ball and envelop part of the forward portion of the ball and expand against the wall of the bore.

IRVING W. EDWARDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

